The present invention relates to a webbing insertion member, such as used with a shoulder webbing of a seat belt system.
As well known in the art, seat belt systems are installed in high-speed vehicles, such as automobiles and aircraft, for protecting occupants by means of webbing thereof. For example, as for a seat belt system for a front seat of an automobile, the webbing is suspended by a webbing insertion member disposed on a B-pillar of the automobile.
FIG. 7 is a general view showing an example of a seat belt system for an occupant in a vehicle front seat and FIG. 8(a) is a rear view (seen from a pillar side) showing a structural example of a conventional insertion member used for the seat belt system.
The seat belt system has a webbing 10 of which one end is connected to a retractor 12 in such a manner as to allow the winding and withdrawing of the webbing 10 and the other end is fixed to a vehicle body by an anchor 14. A portion of the webbing 10 therebetween is passed through an insertion member 16 and a tongue 18, respectively. The retractor 12 is provided with a return spring (not shown) which pulls the webbing 10 in the winding direction. Due to the spring, force in the winding direction is always applied to the webbing 10.
The insertion member 16 is provided with a bolt hole 22, formed in an upper portion thereof (FIG. 8(a)), for the installation to a B-pillar 20 and a webbing-through opening 24 formed in a lower portion thereof, the webbing-through opening 24 having a slit-like shape extending long in the width direction of the insertion member 16. Existing below the webbing-through opening 24 is a bearing portion 26 extending in the width direction of the pillar.
The webbing 10 withdrawn from the retractor 12 is passed through the webbing-through opening 24 and is suspended on the bearing portion 26 so that the webbing 10 is slidable along the outer surface of the bearing portion 26 in the winding and withdrawing direction.
The member 16 is positioned such that the width direction thereof extend along the longitudinal direction of the vehicle and is installed to the B-pillar 20 by the bolt 28 through the bolt hole 22 such that the member 16 can rock about the bolt 28 and pivot to the left or right (in the longitudinal direction of the vehicle). Though the insertion member 16 is fixed to the B-pillar 20 directly by the bolt 28 in this conventional example, the insertion member 16 is often installed to a height adjuster, vertically disposed on the B-pillar 20, with a bolt or the like.
In the seat belt system for an automobile having the aforementioned structure, when it is desired to wear the seat belt an occupant pulls the webbing 10 from the retractor 12 and puts the webbing 10 across the front of the occupant's body. The portion of the webbing 10 between the insertion member 16 and the tongue 18 is called as a shoulder belt portion 11. Then, a tongue plate 19 of the tongue 18 on the webbing 10 is latched with a buckle 30, thereby securing the webbing 10 around the occupant. For releasing the wearing of the webbing 10, the tongue 18 is released from the buckle 30 by pressing a release button 31 of the buckle 30. Then, the webbing 10 is wound by the winding force of the retractor 12. The webbing 10 slides along the outer surface of the bearing portion 26 in both cases of withdrawing the webbing 10 and of winding the webbing 10 into the retractor 12.
The retractor 12 may have a pretensioner mechanism and an EA (energy absorbing) mechanism incorporated therein. The pretensioner mechanism is provided for winding up a predetermined length of the webbing 10 in an emergency situation such as a vehicle collision, in order to securely restrain the occupant to a vehicle seat. The EA mechanism is provided for allowing the webbing to be gradually withdrawn from the retractor when a predetermined load is applied to the webbing 10 by the occupant after the webbing 10 is wound by the operation of the pretensioner mechanism, in order to absorb the impact exerted on the occupant.
The shoulder belt portion 11 is positioned on the vehicle front side (the right in FIG. 8(a)) from the insertion member 16 when the seat belt is worn as shown by two-dotted lines in FIG. 8(a).
In this state, as the pretensioner mechanism or the EA mechanism is actuated so that the webbing 10 is rapidly and strongly wound into the retractor 12 or suddenly withdrawn from the retractor 12, the webbing 10 may shift to the vehicle front side or the vehicle rear side along the bearing portion 26 so that the webbing 10 is inclined within the webbing-through opening 24 as shown in FIG. 8(b). It should be noted that this situation also depends on the size and the attitude of the occupant, the position and the reclining angle of the vehicle seat, and the layout of the vehicle cabin.
The webbing 10 may be inclined within the opening 24 not only with the winding or withdrawing of the webbing due to the actuation of the pretensioner mechanism or the EA mechanism, but also with the normal winding or withdrawing of the webbing 10 due to the position of the B-pillar 20, the installation angle of the insertion member 16, the position of the vehicle seat, the layout of the vehicle cabin, and/or the attitude or the size of the occupant, for example, even when the retractor 12 does not include the pretensioner mechanism or the EA mechanism.
When the webbing 10 is significantly inclined, the webbing 10 is gathered and locally stressed by large tension as shown in FIG. 8(b). To withstand this, the webbing 10 is required to have large tensile strength, thus increasing the cost.